Astrometric Catalogue Epoch Mismatch Years Delta Calculator
Signed second−first reference-epoch mismatch in same Julian epoch convention; no motion correction or Besselian/Julian mixing. Caller independently establishes frames, units, epoch, covariance and instrument context; not an identity, association or astrometric quality certification.
Description
Catalog epochs determine the time separation between recorded reference states.
Catalog epochs determine the time separation between recorded reference states.1
Epoch subtraction alone does not propagate coordinates or correct proper motion. Use Astrometric Catalogue Epoch Mismatch Years Delta Calculator to evaluate the supplied inputs under the model explained below.
When to use Astrometric Catalogue Epoch Mismatch Years Delta Calculator
Use Astrometric Catalogue Epoch Mismatch Years Delta Calculator to evaluate the supplied inputs under the model explained below. Establish the units, measurement scope and model assumptions before entering values.
How to use Astrometric Catalogue Epoch Mismatch Years Delta Calculator and understand its results
- Establish the units, measurement scope and model assumptions before entering values.
- Enter First catalogue julian epoch, Second catalogue julian epoch using the field table and validation rules below, then run the tool.
- Read Signed epoch difference julian years; interpret the units, signs, ordering and unknown-value placeholders described below.
- Correct reported input errors and rerun. Apply successful results according to their specific meanings and check the assumptions before using them in a decision.
| Input field | Meaning | Value type | Requirement |
|---|---|---|---|
| firstCatalogueJulianEpoch | First catalogue julian epoch | number | Required; constraints below |
| secondCatalogueJulianEpoch | Second catalogue julian epoch | number | Required; constraints below |
Enter finite first and second Julian epochs. Return second−first in Julian years, preserving negative differences. No coordinate propagation or conversion between epoch conventions occurs.
epochDifferenceJulianYears=secondEpoch−firstEpoch Use the field order, units and branch conditions described above.
| Output field | Meaning | Value type |
|---|---|---|
| signedEpochDifferenceJulianYears | Signed epoch difference julian years | number |
{
"input": {
"firstCatalogueJulianEpoch": 2000,
"secondCatalogueJulianEpoch": 2016
},
"output": {
"signedEpochDifferenceJulianYears": 16
}
}Limitations and assumptions
Epoch subtraction alone does not propagate coordinates or correct proper motion. Apply the exact scope and assumptions explained above.
All listed fields require explicit values. Unexpected fields, incorrect types, nonfinite numbers and sparse arrays fail validation. Domain-specific bounds, alignments and supported tokens are explained above; extremely large inputs or outputs can also be rejected. Input errors differ from successful false results, empty match lists and unknown-evidence placeholders.
Alternative or Complementary methods
Use Julian Epoch from Calendar Date Fractional Year Calculator for a related task: A Julian epoch uses a fixed-length Julian year referenced to a particular Julian date.
Use Besselian Epoch from Year Start Offset Calculator for a related task: A Besselian epoch uses a different reference and year length from a Julian epoch.
References
Similar or alternative tools
- Julian Epoch from Calendar Date Fractional Year Calculator
A Julian epoch uses a fixed-length Julian year referenced to a particular Julian date.
- Besselian Epoch from Year Start Offset Calculator
A Besselian epoch uses a different reference and year length from a Julian epoch.